A DETAILED OVERVIEW OF GEOSTATIONARY SATELLITES: EXCLUSIVE FEATURES OF GEO SATELLITES
- Ananya Sharma
- Mar 3, 2024
- 4 min read
Updated: Apr 5, 2024
Hello, Everyone!
Today’s era has its ground standing on improved telecommunication. Over the years, the way we communicate across various areas, telecommunication has been a cornerstone and played a pivotal role in revolutionizing communication. But what is telecommunication? We can understand telecommunication or telecom as the channeling or we can say transmission of information through a range of technologies over wire, radio, optical, or other electromagnetic systems.
But the era of telecom has witnessed a leap in recent years, completely changing the way we keep contact worldwide post the developments in communication satellites. A satellite is an object which revolves around a larger object. For instance, Earth is a satellite since it revolves around the Sun. Various types of satellites meet the requirements of different organizations.
Depending upon the purpose of communication satellites, these satellites have different onboard technology, equipment, and orbital paths.
Geostationary Satellites are indispensable for the pursuit of improved communication which includes television, radio as well as satellite phones.
Let’s delve into the intricacies of the geostationary satellite and have a detailed overview of the same.
About Geostationary Satellite:
The geostationary satellite revolves around the Earth in a curved path called an orbit due to the gravitational force of the Earth, placed at an altitude of 22,300 miles or 35,800 Km above the equator.
1. The Geostationary satellite revolves in the direction of the earth's rotation i.e. from West to East.
2. They appear stationary in the sky to an observer based on the ground that’s why the name Geostationary satellite.
3. They complete one orbit in 24 hours, the same time Earth takes to rotate once on its axis. Since the satellite moves in perfect sync with the Earth’s rotation therefore it appears as a stationary object to an observer from the ground.
About Geostationary Orbit:
The Geostationary Orbit or the geosynchronous equatorial orbit (GEO)is a circular geosynchronous orbit having an altitude of 35,800Kms above Earth’s equator, a radius of 42,164Km from the Earth’s center, and the same direction as Earth's rotation.
Another major advantage is that the orbit is about 99% of times the orbit is Sunlit
With an altitude of 35,800 km, the altitude is quite above the high-intensity radiation belt and above the most intense region of the significantly milder outer belt. Therefore enough protection is obtained with marginal weight.
Geostationary Satellites Provisioned With:
The Geostationary Satellites have transponders and it does amplification of the received radio signal and also the frequency translation. A radio signal or we can say a wave is somewhat electromagnetic radiation having a frequency of 300 GHz (Gigahertz) and below. These waves possess the longest wavelength in the electromagnetic spectrum.
An amplification of a received signal, also called increasing the power of a received signal happens when the signals are received from the Earth which are by nature very weak due to the large distance involved. The amplification is done by a low-noise amplifier (LNA).
Post that the received radio signal (uplink) undergoes a down-conversion, by a carrier processor.
Lastly, the power of the frequency down-converted signal (downlink) is amplified to a desired level by a power amplifier.
The final power-amplified downlink signal is retransmitted back to the satellite antenna by a duplexer.
A wide range of applications are possible with these signals such as telecommunications, broadcasting, remote sensing as well as navigation.
Working of the Geostationary Satellite:
A satellite is first launched into the transfer orbit which is an elliptical orbit, enabling the satellite to move to its final high altitude by using comparatively little energy deriving out of the inbuilt motors. The transfer orbits are required so that there is a need for the launch vehicle to completely go to the final altitude.
Thrusters and reaction wheels help keep the satellite maintain its position in space relative to the rotation of the Earth by enabling the satellite to make little adjustments to its position as required to maintain its orbit at the same speed as the Earth’s rotation and also in the same position above the Earth’s equator.
Here the altitude of an orbit of a satellite plays a vital role. An altitude of 22,300 miles is what is required by a satellite to achieve a 24-hour orbit. The orbit at such altitude keeps the satellite fixed over one longitude at the equator.
The satellite seems stationary at a fixed position in the sky to the ground observers.
Longitude or the meridians are the vertical lines from the East or west of the prime meridian at Greenwich or 0-degree longitude.
Line of Sight of Geostationary Satellite:
The line of sight of a geostationary satellite is a path between the satellite and the ground station. About one-third of the earth's surface is covered by a single geostationary satellite. The GeoSat orbit gives the information from 20 degrees north to 20 degrees south latitude.
We can say that the satellite can see one-third of the earth’s surface wherever it is kept above the equator.
Therefore we can infer that about 3 GeoSats are needed with each separated by 120 degrees of longitude to have an entire plane coverage, excluding the circular regions over the north and the south geographic pole.
Uses of Geostationary Satellite:
They are used to:
1. Study meteorological events,
2. Understand the topography
3. Weather prediction
4. Explore the outer space
5. Surveillance
6. GPS
7. Communication
8. Monitoring of Power Lines
9. Useful in studying radiation of cosmic rays
Limitation of Geostationary Satellites:
Although Geostationary satellites have a wide range of advantages still there are some limitations associated with them such as
1. A smaller number of satellites can be placed at an orbit of 0 degrees from the equator as the orbit is a narrow ring which might result in conflicts or collisions.
2. The circular regions over the north and the south geographic poles are left out by them.
3. These are high on expenses as launching them into high altitudes requires large fuel and energy.
4. An electromagnetic signal of exactly 71,500 Kms is a pre-requisite for it to be sent to and fro from these satellites. A slight variation in the wavelength can lead to breakdown or delays.
5. There is a high probability of electromagnetic radiation noise if the satellite is near the Sun as the Sun is the prime source of electromagnetic radiation.
Thank You.
References:
Commentaires